The present invention relates generally to offset benders and, more specifically, to one-step offset benders for pipe and other materials.
Conduit bending is one of the fundamental tasks of the electrical construction industry. For example, conventional electrical wiring installations may use EMT (electrical metallic tubing), galvanized steel conduit, or intermediate conduit for protecting runs of wiring. Installation of the conduit generally requires following a path that may be irregular and may include protuberances and other irregularities that must be negotiated. Very frequently, a step-type bend is required, wherein a straight length of conduit is bent twice such that the end portions of the conduit are parallel but offset. This is commonly referred to as an xe2x80x9coffset bend.xe2x80x9d It will be appreciated that an offset bend typically requires two equal and opposite bends in the conduit.
When the conduit must be bent to generally go around or over an obstacle in an otherwise linear path, two complementary offset bends are made, producing what is commonly called a xe2x80x9csaddle bend.xe2x80x9d A saddle bend generally requires four bends in the conduit, which bends are all equal, with two bends opposite in direction to the other two bends.
Often a number of parallel runs of conduit are required. In such cases, it is desirable that the offset bends for all of the parallel runs be very nearly identical, in order to have an easily followed and aesthetically pleasing result. Producing a good, consistent offset bend, however, requires practice, and can be difficult and time-consuming even for experienced installers. Moreover, if an error is made in an offset bend or saddle bend, the conduit may be rendered unusable.
With a conventional bender, a mechanic in the trade typically bends one end of the pipe a selected amount, and then calculates the appropriate the location and angular amount for a second bend that must be accomplished to achieve a specified offset, while accounting for the xe2x80x9cconduit shrinkagexe2x80x9d caused by the bent portion of the conduit. This is a time-consuming process and can be less than a science. It may take hundreds of hours to learn the skill to make a good offset bend. Another problem with conventional benders is that if the pair of bends are not appropriately aligned, i.e., precisely at 180 degrees opposite, you get what is called a xe2x80x9cdog leg,xe2x80x9d wherein the offset end is not parallel to the starting end. Even when everything is done right and efficiently, it simply takes time to carefully produce two separate bends in a conduit.
A conventional conduit bender includes a conduit shoe having a curved groove that is sized generally to receive the conduit, and a ring or hook element near the end of the groove that is adapted to hold the end of the conduit in alignment during the bending process. An example of a conduit shoe is disclosed in U.S. Pat. No. 4,269,056 to Kozinski. As disclosed by Kozinski, the conduit shoe, or conduit bender, has a rocker base portion formed by a pair of laterally spaced, curved sidewalls that define a longitudinally extending conduit-receiving groove therebetween. A hook is formed at one end of the rocker base portion. Other suitable, somewhat similar conduit shoe members for bending conduit are in common use and are well known in the field. Such suitable shoes are simply referred to as xe2x80x9cconduit shoesxe2x80x9d herein.
It will also be appreciated that, although the present invention is described with reference to conduit, it is also suitable for producing offset bendsxe2x80x94including, for example, saddle bendsxe2x80x94in other tubular materials or other materials, such as metal pipe for water, gas, or the like. Producing such bends in other tubular materials may be particularly important in applications where space is tight and/or the desired routes for such materials are not straight and/or regular, such as in boats, ships, and other vehicles. It should be understood that the term xe2x80x9cconduit,xe2x80x9d as used herein, includes any metal tubular or other-shaped material and, in particular, is not restricted to tubing used for housing wiring.
Although devices for producing offset bends in one step in pipe, conduit, and other materials have been proposed, prior art offset benders have one or more disadvantages. For example, they often are not suitable for producing large offset bends (over one inch) in a single step; they may require mechanical assistance and/or leverage; they cannot accommodate different-sized materials; they often are large and difficult to transport to a construction site; they can be difficult to use; they may not permit easy removal of the bent pipe or conduit; and may not produce repeatable or sufficiently accurate offset bends.
While conventional offset benders may be suitable for the particular purpose to which they address, they are not as suitable for speed and accuracy in offsetting pipe or other materials. In these respects, the one-step offset bender, according to the present invention, substantially departs from the conventional concepts and designs of the prior art, and in so doing, provides an apparatus primarily developed for the purpose of improving speed, accuracy, and portability in offsetting pipe or other materials.
In view of the foregoing disadvantages inherent in the known types of offset benders now present in the prior art, the present invention provides a new one-step offset bender construction wherein the same can be utilized for speed and accuracy in offsetting pipe or other materials.
The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new one-step offset bender that has many of the advantages of conventional conduit benders and novel features that result in a new one-step offset bender that is easy to use, easy to manufacture, and easily transportable.
To attain this, the present invention generally comprises: (i) a base; (ii) a first shoe support; (iii) a first shoe assembly attached to the first shoe support, the first shoe assembly including at least one conduit shoe; (iv) a second shoe support that is movable horizontally with respect to the first shoe support; and (v) a second shoe assembly that is movable vertically with respect to the first shoe assembly, the second shoe assembly including at least one conduit shoe. The conduit shoes include a curved radius with a curved groove and a hook arm, as are known in the art, that hold one end of the conduit in a substantially horizontal position.
In the preferred embodiment, each shoe assembly includes a plurality of shoes of differing sizes that are pivotally and lockably mounted to the supports, allowing the user to easily select a desired size.
In the preferred embodiment, the frame includes a horizontal rail that movably supports the second shoe support, and the second shoe assembly is mounted on a vertical rail, whereby the second shoe assembly may be moved generally toward and away from the first shoe assembly, and may be moved vertically with respect to the first shoe assembly.
In another aspect of the preferred embodiment, two or more different sized conduit shoes are mounted on opposite ends of a shaft to allow the shoe size to be changed by pulling a pin and spinning the arm 180 degrees and replacing the pin. A single set of shoes may be used with different sized.
In yet another embodiment of the invention, a motor is used to provide motive power for vertically moving the second shoe assembly. The motive power may be provided with and electric motor, hydraulically, or the like.
In this respect, before describing one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting.
An object of the present invention is to provide a one-step offset bender for speed and accuracy in offset bending of pipe or other materials.
Another object of the present invention is to provide a one-step offset bender that makes a straight or true offset in a pipe, conduit, or flat stock in one bend. One of the problems to overcome was that the overall length gets shorter as the material is bent.
Another object is to provide a one-step offset bender that will save time on the job. It may incorporate a built-in guide, so one can read the guide instead of getting out a measuring tape.
Another object is to provide a one-step offset bender that will provide a more uniform outcome on parallel runs of pipe.
Another object is to provide a one-step offset bender that, for smaller uses, could be transported and handled by one person, put in a truck, and used on a small site.
Other objects and advantages of the present invention will become obvious to the user, and it is intended that these objects and advantages are within the scope of the present invention.